Television receiver with ultra high frequency cavity tuner inside very high frequency turret tuner



J. O. SILVEY Aug. 22, 1961 1 a 5 owww 2 m TELEVISION RECEIVER WITH ULTRAHIGH FREQUENCY CAV TUNER INSIDE VERY HIGH FREQUENCY TURRET TUNEROriginal Filed Aug. 9, 1952 INVENTOR- JOHN 0. SILVEY AZ ATTORN 1961 .1.o. SILVEY 2,997,582

TELEVISION RECEIVER WITH ULTRA HIGH FREQUENCY CAVITY TUNER INSIDE VERYHIGH FREQUENCY TURRET TUNER Original Filed Aug. 9, 1952 4 Sheets-Sheet 2mmvrox.

JOHN o. SILVEYJ ATTORNEY Aug. 22, 1961 J. o. SILVEY 2,997,582

TELEVISION RECEIVER WITH ULTRA HIGH FREQUENCY CAVITY TUNER INSIDE VERYHIGH FREQUENCY TURRET TUNER Original Filed Aug. 9, 1952 4 Sheets-Sheet 3l g o v mm W I I i.

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Aug. 22, 1961 J. o. SILVEY 2,997,582

TELEVISION RECEIVER WITH ULTRA HIGH FREQUENCY CAVITY TUNER INSIDE VERYHIGH FREQUENCY TURRET TUNER Original Filed Aug. 9, 1952 4 Sheets-Sheet 4ii iil'llllllllllulm i I i .57 55 fr A FIG? 67 FIG.8

INVENTOR.

JOHN O. SILVEY ATTORNEY Unit TELEVISION RECEIVER WITH ULTRA HIGH FRE-QUENCY CAVITY TUNER INSIDE VERY HIGH FREQUENCY TURRET TUNER John 0.Silvey, Fort Wayne, Ind., assignor to Intemational Telephone andTelegraph Corporation, a corporation of Maryland Original applicationAug. 9, 1952, Ser. No. 303,457,

now Patent No. 2,800,581, dated July 23, 1957. Divided and thisapplication Oct. 24, 1957, Ser. No.

7 Claims. (Cl. 250-20) I-F frequency for which the LP stage is aligned.The

R-F frequencies presently allocated to commercial tele vision, fallwithin the very high frequency (VHF) band, and therefore, the tunersdesigned for present day television receivers may be designated VHFtuners.

With the advent of allocating ultra high frequencies (UHF) forcommercial television, there has arisen the problem of designing UHFtuners which may be practically and economically incorporated in thepresent day television receiver. Many different types of UHF tuners havebeen developed, which, like the VHF tuner, are assembled and aligned asseparate units. Although in a technical sense they have been made tooperate satisfactorily, they are costly and bulky, thereby materiallyincreasing the cost of the receiver.

It is the object of this invention to provide a combination VHF-UHFtuner contained in a single unit, which is efficient and economical.

.It is a further object of this invention to provide a tuner, of theturret type, for both the VHF and UHF frequency bands.

Another object of the invention is to provide a combination tunerwherein many of the same components are utilized for both VHF and UHFtuning.

Another object of the invention is to provide a unique UHF tuner whichis simple and efiicient.

In accordance with one aspect of the invention, there is provided a VHFtuner comprising means for selecting a signal :of a given VHF frequency,and means for reducing the frequency of the VHF signal to apredetermined I-F frequency. In combination with the VHF tuner, there isprovided a UHF tuner electrically and mechanically coupled therewith andpositioned interiorly of said VHF tuner. The UHF tuner comprises meansfor selecting a signal of a given UHF frequency and means .for reducingthe UHF frequency to the predetermined I-F frequency. The LP signalproduced by the UHF tuner is then injected into the VHF tuner, which nowoperates simply as an amplifier.

States Patent 2,997,582 Patented Aug. 122, 1961 ICC 2 best understood byreference to the following description of an embodiment of the inventiontaken in conjunction with the accompanying drawings, in which:

FIG. 1 shows schematically a diagram of the circuits comprising a VHFtuner;

FIG. 2 shows schematically a diagram of the UHF tuner, forming anembodiment of the invention; and

FIGS. 3-8 show the mechanical construction of the combination VHF-UHFturret tuner: the FIGS. 5-7 representing sections taken alongcorresponding lines of FIG. 3; and FIG. 8 showing a section taken alonglines 8-8 of FIG. 4.

Referring now to FIG. 1 there is shown the VHF tuner comprising an R-Famplifier section 1, a local oscillator 2 and a converter 3. The desiredchannel is selected by switching the turret tuner (shown in FIG. 4),whereby the proper sets of coils are inserted into the amplifier,converter and oscillator circuits. Since turret tuners are well known tothe art, the mechanical operation of the tuner will not be described,except as it affects the novelty of this invention. Further, thecircuitry shown by FIG. 1 is known to the art and, therefore, thedetailed operation of each of the component parts will be omitted fromthe explanation.

The signal from an antenna is coupled through tuned antenna inputcircuits 4, 5, to the first R-F stage through a center tappedtransformer indicated at 6. The R-F signals are fed to the grid of tube7 and are amplified in this circuit, which is the first stage of atwo-stage amplifier. The two-stage amplifier may be of the type known asa driven grounded-grid R-F amplifier. The plate circuit of the secondstage .8, of the R-F amplifier,

is tuned 'by the inductance of the primary winding 9 of the mixer inputcoil in conjunction with the parallel combination of capacitor 10 andtube output capacitance in series with capacitor 11. Capacitor 10 is anadjustable trimmer capacitor. The primary winding 9 is the plate loadfor the R-F amplifier 8; resistor 12 is provided to broaden the responseof this circuit.

A pentode-triode type tube may be employed as a mixer-oscillator tube;one section 13 being used as a mixer and the other section 14, as theoscillator. The grid circuit of the mixer tube receives the R-F signaland oscillator signal from the secondary 15 of the mixer invput coilwhich is inductively coupled to both the oscillator and R-F amplifier.Grid leak bias for the mixer is developed by capacitor 16, resistors 17and 18. Capacitor 16 is an adjustable trimmer capacitor for peaking themixer grid circuit. Coil 19, which provides the plate load for themixer, is by-passed by capacitor 20 in order to prevent regenerativefeedback in the mixer. Adjustable coil .21 couples the mixer output tothe first I-F amplifier stage.

The second half of the tube is employed as a modified Colpitts typeoscillator. The oscillator coil 23 is inductively coupled to the mixergrid via mixer coil 15 for oscillator injection. Capacitors 24 and 25form the split capacitor of the Colpitts oscillator. Capacitor 24 may bea variable dielectric type capacitor used for oscillator fine tuning.

Thus, operating as'a VHF tuner, the RF tuned ampiifier 1 selects asignal of a given frequency in the VHF band and applies this signal tothe grid of the mixer 3. The oscillator 2 provides a local frequencywhich is applied to the mixer, where it, togetherwith the R-F signal, isheterodyned and converted to an LP frequency. The output from the mixeris then applied to the first I.-F stage.

Referring now to FIG. 2, the UHF tuner, shown schematically, comprises,preferably, a tuned antenna circuit of the coaxial line type 26, tunableby a variable-plunger type capacitor 27 at the open end of aquarter-wave line.

3 The tuned antenna line may be aperture-coupled to a tuned crystaldetector line 28, tunable by a variable capacitor 29 at the open end ofthe quarter-wave line. The proper local frequency is selected by aharmonic selector line 30, tunable by a variable capacitor 31 at theopen end of the quarter-wave line. The line 30 is tuned to athird'harmonic of the VHF oscillator and may be loopcoupled shown at 32to the mixer line. The oscillator of the VHF circuit is tuned to onethird-frequency of the UHF frequency by a variable oscillator line 33coupled to a variable oscillator coil 34 which is inserted into the VHFoscillator circuit for UHF reception. The variable capacitors 27, 29 and31 respectively, and the variable inductance 34 are ganged mechanicallyas indicated at 35.

grid tuning for the first stage of the R-F amplifier 1. The

Since the VHF tuner operates into a 41.25-45.75 me. I-F

amplifier, also in accordance with present day standards, then at UHFthe R-F amplifier and mixer provide additional I-F amplification tocompensate for the conversion loss, and absence of R-F amplification.

When the tuner is switched from VHF to UHF, the component strips shownby dotted lines in FIG. 1 are switched out of circuitry and thecomponent strips shown in FIG. 2, are switched into circuit operatingconnection. Therefore, coil 9a replaces coil 9 in the plate circuit ofamplifier 8, coil 15a replaces 15, coil 34 replaces 23, etc. Theterminals represented by lettered circles AJ indicate the position atwhich the coils are connected into the circuit.

As best seen in FIGS. 3, 4, 5 and 8, housing 38 is provided for theturret tuner 39. The turret tuner comprises a pair of spring plates 40and 41 respectively '(FIG. 5) positioned at either ends of the turret tosecure 'the outer ends of circuit component panels generally indicatedat 42 and 43. The spring plates are fastened port 49 by means such asscrews 49a. The other ends of the panels 42, 43 are secured in place bya scallop shaped disk 44 (FIG. 3) positioned intermediate the springplates 40 and 41 respectively. Suflicient scallops are formed on disk 44to provide 13 positions; each position being referenced by the detentsin the scallop. A detent spring 45 (FIGS. 4, 8) attached to the turrethousing 38 forces a detent spring wheel 46 to ride on the scallopsurface of the disk 44. The turret 39 is rotated (described hereinafter)to a UHF tuner cylinder or sup- 9 by a tuning dial knob 47 coupled tothe turret by a shaft 48 (FIGS. 4, 5).

The structure of the turret tuner for the VHF circuit components isdescribed and claimed in Patent No. 2,706,252, granted April 12, 1955.

Interiorly of the VHF turret component members,

there is mounted on the shaft 48 (FIG. 5) the UHF tuners assembly. TheUHF tuner assembly is mounted in a cylinder 49 and comprises the tunablequarter-wave lines illustrated in FIG. 2.

Referring to FIG. 6,. which is a section taken along I coaxial line 55is grounded to a portion of the tuner chassis 59and rotatable thereon.The antenna contact 4 57 is made rotatable to permit rotation of thetuner assembly without twisting the antenna input leads.

Referring for a moment to FIG. 2, the oscillator line 33, which operatesas a variable tuned circuit, is tuned to one-third frequency of the R-Fenergy. The third harmonic of the oscillator energy is taken from theplate circuit of oscillator 14 and fed to the harmonic selector line 30.As best seen in FIG. 5, the tuning oscillator, corresponding tooscillator line 33 and coil 34 shown in FIG. 2, comprises an oscillatorcavity 60 which is tuned by an oscillator plunger 61 at the open end ofthe line. Capacitance is provided by capacitor plate 62.

The R-F energy from the antenna line 26 is coupled to the mixer line 28(FIG. 5) by means such as aperture coupling 64 (FIG. 3). The mixer line28 is preferably tuned by a plunger type capacitor 65.

The R-F energy and the oscillator energy are mixed preferably in acrystal type mixer 37 (corresponding to detector 37 of FIG. 2). Aby-pass may be provided for the R-F energy by a capacitor of low valueinductance 71.

Referring now to FIG. 7, a coaxial line corresponding to harmonicselector line 30 (FIG. 2) is fed by an oscillator injection line 67. Thecoaxial line 30 is tuned by means of a plunger type capacitor 68 to thethird harmonic of the local oscillator, which according to present daystandards is preferably 41.25 mc. above the RF antenna line frequency.

The harmonic selector line 30 is coupled to the mixer line 28 byaperture coupling 69 and a coupling loop 32 (FIGS. 2, 3).

As may best be seen in FIG. 4, the UHF tuning is accomplished byrotating a UHF tuning knob 74, which is coupled to a drive sleeve 75 fordriving a pulley 76. The pulley 76 transmits power through a drive chain77 to the UHF tuning pulley 78. The UHF tuning pulley 78 is secured to atuning sleeve 79 which linearly drives a UHF tuning plunger drive plate80 (FIGS. 4, 5). The UHF tuning sleeve 79 also drives the UHF tuningdial 81. The details of the dial tuning device is explained in US.Patent No. 2,775,896, filed January 1, 1957. The drive plate 80 is inthe form of a disk having a centrally tapped hole to accommodate thethreaded sleeve drive 81 which is formed at one end of the tuning sleeve79, or it may be a separate member coupled to the sleeve 79. In additionto the centrally tapped hole, there are bored and tapped four holes toengage the threaded ends of the tuning plungers; e.g., ends 82 and 83(FIG. 5). When the sleeve 79 is rotated the drive plate is movedlinearly causing the plungers to move linearly within the cavities andvary the characteristics of the coaxial lines. The ends of the plungersare threaded to permit initial adjustment of the plungers.

Since the same oscillator tube and components, except for tuned circuit33 are used at UHF and at VHF, fine tuning is accomplished for boththrough a fine tuning drive shaft knob 82. The knob 82 is coupled to ashaft 83 which drives cord 84, fine tuning pulley 85, and fine tuningshaft 86. The fine tuning shaft 86 is connected to a fine tuningcondenser 87.

While I have described above the principles of my invention inconnection with specific apparatus, it is to be clearly understood thatthis description is made only by way of example and not as a limitationto the scope of my mvention as set forth in the objects thereof and inthe accompanying claims.

What is claimed is:

1. In combination, a very high frequency tuner com prising means forselecting a signal of a given very high frequency and means for reducingthe frequency of said signal to a predetermined intermediate frequency;an ultra high frequency tuner electrically coupled to said very highfrequency tuner comprising means for selecting a signal of a given ultrahigh frequency, and means for reducing said ultra high frequency to saidintermediate frequency; means for converting said very high frequencyselecting means into intermediate frequency amplifying means; and meansfor injecting said intermediate fre quency signal into said convertedvery high frequency tuner selecting means.

2. In combination, a very high frequency tuner comprising means forselecting a signal of a given very high frequency, local oscillatormeans, and mixer means for heterodyning the frequency of the selectedsignal with the frequency of the local oscillator, to produce apredetermined intermediate frequency; an ultra high frequency tunercomprising means for selecting a signal of a given ultra high frequency,means including the local oscillator means of said very high frequencytuner for producing a given frequency, mixer means for heterodyning thefrequency of said selected ultra high signal with said given frequencyto produce said intermediate frequency, means for converting said veryhigh frequency selecting means into intermediate frequency amplifyingmeans, and means for injecting said intermediate frequency into saidvery high frequency tuner selecting means.

3. The combination according to claim 2, wherein said intermediatefrequency amplifying means further comprises said mixer means.

4. In combination, a very high frequency tuner comprising means forselecting a signal of a given very high frequency, local oscillatormeans, and mixer means for heterodyning the frequency of the selectedsignal with the frequency of the local oscillator, to produce apredetermined intermediate frequency; an ultra high frequency tunercomprising means for selecting a signal of a given ultra high frequency,a tunable coaxial harmonic selector line coupled to said localoscillator means and tuned to a third harmonic thereof, to produce agiven frequency, mixer means for heterodyning the frequency of saidselected ultra high signal with said given frequency to produce saidintermediate frequency, means for converting said very high frequencyselecting means into intermediate frequency amplifying means, aud meansfor injecting said intermediate frequency into said very high frequencytuner selecting means.

5. The combination according to claim 4, wherein said ultra highfrequency selector means and mixer means comprise tunable coaxial lines,and said mixer line is aperture coupled to said selector line andharmonic selector line respectively,

6. The combination according to claim 5, comprising means forcapacitively tuning said coaxial lines, inductive means for varying thefrequency of said local oscillator, and means mechanically coupling saidcapacitive tuning means and said inductive means together, whereby thetuning of each of the coaxial lines and the oscillator may be effectedsimultaneously.

7. The combination according to claim 5, wherein each of said coaxiallines are one quarter wavelength long at the operating frequency andhave one open end respectively, said lines being tunable at the openends thereof.

References Cited in the file of this patent UNITED STATES PATENTS2,798,955 Balash July 8, 1957

